1. Field of the invention
The present invention relates to a mechanism for preventing unintended detachment of a plug which ms for use in an adapter and the like for an optical connector.
2. Description of the Related Art
The conventional plug A for an optical connector is, as shown in FIGS. 7 to 9, constructed in such a way that a plug frame a, which has a transversely-long-quadrangle in cross sectional view, is engaged axially with a metallic ring b and a rubber holder (not shown) is coupled axially to a rear edge portion of the metallic ring b to be mechanically integrated therewith, and also in the center thereof, a ferrule d into the center of which a fiber c is inserted to be bonded thereto is provided through a spring e between the ferule and the metallic ring b by the insertion, and further a lug f is mounted to the outside of the plug frame a so as for the plug frame a to be able to be slid axially within the lug f by a desired stroke L.
In addition, an opening portion g having an approximately rectangular shape is provided so as to spread to the both right and left side faces of a head portion of the lug f. Detent recess portions k which are to be engaged with respective detent projection portions j of a pair of spring-like detent pieces i which are provided in right and left side faces of an adapter h are recessed in both right and left side faces of the plug frame a so as to be positioned in the respective opening portions g.
Further, in right and left inner faces of the opening portion g in the lug f, as shown in FIG. 9, portions n for guiding projections m which are provided on both right and left sides of the pair of spring-like detent pieces i are formed in front portions of horizontal bottoms o so as to have respective inclined faces p each of which is inclined so as to rise outwardly.
Then, when the plug A is inserted into the adapter h, as shown in FIG. 7, the detent projection portions j of the pair of spring-like detent pieces i are engaged with the pair of detent recess portions k of the plug A by the elastic deflection and the ferrule d of the plug A is mated with a guide tube q within the adapter h. Then, this mating state is held by the engagement between the detent projection portions j of the spring-like detent pieces i and the detent recess portions k.
In addition, when a pull-out force is applied to the lug f of the plug A, as shown in FIG. 8, the pair of spring-like detent pieces i are elastically deformed outwardly as the projections m which are provided on the both sides of the detent pieces i are guided into the respective inclined faces p in the guide portions n of the plug A while the lug f is slid to the back side (in the right direction in the figure) by a predetermined stroke L with respect to the plug frame a by that pull-out force, whereby the engagement between the detent projection portions j and the associated detent recess portions k is released.
Thus, since the above-mentioned prior art plug is easily detached by using a hand or tool, other plugs other than a predetermined plug in connection may be detached by mistake in some cases. This inadvertent, unintended, or erroneous detachment inadvertent of the plug hereinafter referred to as maldetachment of the plug, may occur particularly in the connectors used in conjunction with LAN or the like in which optical transmission lines are distributed with high density.